stipple_gen/stipple_gen.pde

/*
 
 Modified by Matt McWilliams 2021

 stipple_gen

 This application is intended to replace the original UI of StippleGen_2 with
 a simple Processing application that can be run using command line arguments or
 a config file. Arguments take precedence over the config file.

 Why do it this way? So that the stippling process can be run headless with a config file
 storing the majority of the settings and the command line arguments handling things
 such as input and output file names. Why do that? So this process can be tied into
 automated image generation processes.

 Begrudgingly but respectfully releasing this in accordance with the original LGPL license, 
 though I would prefer to use MIT or ISC which I consider to have fewer encumbrances.

 *******************************************************************************
 HISTORY
 *******************************************************************************

 Program is based on StippleGen_2 
 
 SVG Stipple Generator, v. 2.31
 Copyright (C) 2013 by Windell H. Oskay, www.evilmadscientist.com
 
 Full Documentation: http://wiki.evilmadscience.com/StippleGen
 Blog post about the release: http://www.evilmadscientist.com/go/stipple2
 
 An implementation of Weighted Voronoi Stippling:
 http://mrl.nyu.edu/~ajsecord/stipples.html
 
 *******************************************************************************
 
 StippleGen_2 is based on the Toxic Libs Library ( http://toxiclibs.org/ )
 & example code:
 http://forum.processing.org/topic/toxiclib-voronoi-example-sketch
 
 Additional inspiration:
 Stipple Cam from Jim Bumgardner
 http://joyofprocessing.com/blog/2011/11/stipple-cam/
 
 and 
 
 MeshLibDemo.pde - Demo of Lee Byron's Mesh library, by 
 Marius Watz - http://workshop.evolutionzone.com/
 
 Requires Toxic Libs library:
 http://hg.postspectacular.com/toxiclibs/downloads
 
 */

/*  
 * 
 * This is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * http://creativecommons.org/licenses/LGPL/2.1/
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */ 

import toxi.geom.*;
import toxi.geom.mesh2d.*;
import toxi.util.datatypes.*;
import toxi.processing.*;

// helper class for rendering
ToxiclibsSupport gfx;

import javax.swing.UIManager; 
import javax.swing.JFileChooser; 

public class Config {

  private String filePath;
  private File file;
  private String[] data;

  public int canvasWidth = 800;
  public int canvasHeight = 600;

  public boolean display = true;
  public int windowWidth = 800;
  public int windowHeight = 600; 

  public boolean invert = false;

  public boolean selectInput = false;
  public String inputImage;
  public String outputImage;
  public String outputSVG;

  public int centroidsPerPass = 500;
  public int testsPerFrame = 90000; //
  public int maxGenerations = 5; //number of generations

  public float minDotSize = 1.25;  //2;
  public float maxDotSize;
  public float dotSizeFactor = 4;  //5;

  public int maxParticles = 2000;   // Max value is normally 10000.
  public float cutoff =  0;  // White cutoff value

  public boolean gammaCorrection = false;
  public float gamma = 1.0;
  
  public boolean fill = false;
  public float line = 1.0;

  public Config (String inputFile) {
    int index;
    String[] parts;
    file = new File(inputFile);
    filePath = file.getAbsolutePath();
    boolean exists = file.isFile();

    filePath = file.getAbsolutePath();
    exists = file.isFile();

    index = argIndex("--config");
    if (index == -1) {
      index = argIndex("-c");
    }

    if (index > -1) {
      file = new File(args[index + 1]);
      filePath = file.getAbsolutePath();
      exists = file.isFile();
    }

    if (exists) {
      println("Using config " + filePath);
      file = new File(filePath);
      data = loadStrings(filePath);
    }

    if (data != null) {
      for (int i = 0; i < data.length; i++) {
        parts = splitTokens(data[i], "=");
        setVar(parts[0], parts[1], filePath);
      }
    }

    if (args != null) {
      for (int i = 0; i < args.length; i+=2) {
        if (args[i].startsWith("--")) {
          setVar(args[i].substring(2), args[i+1], "args");
        } else {
          setVar(args[i], args[i+1], "args");
        }
      }
    }
  }

  private int argIndex (String arg) {
    int index = -1;
    if (args != null) {
      for (int i = 0; i < args.length; i++) {
        if ( args[i].startsWith(arg) ) {
          index = i;
        }
      }
    }
    return index;
  }

  private int intOrDie (String name, String val) {
    int intVal = -1;
    try {
      intVal = parseInt(val);
    } catch (Exception e) {
      println("Error parsing value " + name);
      println(e);
      exit();
    }
    return intVal;
  }

  private boolean boolOrDie (String name, String val) {
    String[] truthy = { "true", "on", "t" };
    String[] falsey = { "false", "off", "f" };
    boolean boolVal = true;
    String compare = val.trim().toLowerCase();
    for (int i = 0; i < truthy.length; i++) {
      if (truthy[i].equals(compare)) {
        boolVal = true;
        break;
      }
    }
    for (int i = 0; i < falsey.length; i++) {
      if (falsey[i].equals(compare)) {
        boolVal = false;
        break;
      }
    }
    return boolVal;
  }

  private float floatOrDie (String name, String val) {
    float floatVal = -1;
    try {
      floatVal = parseFloat(val);
    } catch (Exception e) {
      println("Error parsing value " + name);
      println(e);
      exit();
    }
    return floatVal;
  }

  private String strOrDie (String name, String val) {
    return val.trim();
  }

  public void setVar (String name, String val, String source) {
    switch (name) {
      case "canvasWidth" :
        canvasWidth = intOrDie(name, val);
        break;
      case "canvasHeight" :
        canvasHeight = intOrDie(name, val);
        break;
      case "display" :
        display = boolOrDie(name, val);
        break;
      case "windowWidth" :
        windowWidth = intOrDie(name, val);
        break;
      case "windowHeight" :
        windowHeight = intOrDie(name, val);
        break;
      case "invert" :
        invert = boolOrDie(name, val);
        break;
      case "inputImage" :
        inputImage = strOrDie(name, val);
        break;
      case "outputImage" :
        outputImage = strOrDie(name, val);
        break;
      case "outputSVG" :
        outputSVG = strOrDie(name, val);
        break;
      case "centroidsPerPass" :
        centroidsPerPass = intOrDie(name, val);
        break;
      case "testsPerFrame" :
        testsPerFrame = intOrDie(name, val);
        break;
      case "maxGenerations" :
        maxGenerations = intOrDie(name, val);
        break;
      case "minDotSize" :
        minDotSize = floatOrDie(name, val);
        break;
      case "maxDotSize" :
        maxDotSize = floatOrDie(name, val);
        break;
      case "dotSizeFactor" :
        dotSizeFactor = floatOrDie(name, val);
        break;
      case "maxParticles" :
        maxParticles = intOrDie(name, val);
        break;
      case "cutoff" :
        cutoff = intOrDie(name, val);
        break;
      case "gammaCorrection" :
        gammaCorrection = boolOrDie(name, val);
        break;
      case "gamma" :
        gamma = floatOrDie(name, val);
      case "fill" :
        fill = boolOrDie(name, val);
      case "line" :
        line = floatOrDie(name, val);
    }
    println("[" + source + "] " + name + "=" + val);
  }
}

Config config;

final float ACCY    = 1E-9f;

int cellBuffer = 100;  //Scale each cell to fit in a cellBuffer-sized square window for computing the centroid.
int borderWidth = 6;

float imageRatio;
float mainRatio;
float windowRatio;

float lowBorderX;
float hiBorderX;
float lowBorderY;
float hiBorderY;

boolean ReInitiallizeArray; 
boolean fileLoaded;
int SaveNow;
String[] FileOutput; 

String StatusDisplay = "Initializing, please wait. :)";
String lastStatusDisplay = "";
float millisLastFrame = 0;
float frameTime = 0;

String ErrorDisplay = "";
float ErrorTime;
Boolean ErrorDisp = false;

int Generation; 
int lastGeneration = 0;
int particleRouteLength;
int RouteStep; 

boolean showBG;
boolean showPath;
boolean showCells; 

boolean TempShowCells;
boolean FileModeTSP;

int vorPointsAdded;
boolean VoronoiCalculated;

// Toxic libs library setup:
Voronoi voronoi; 
Polygon2D RegionList[];

PolygonClipper2D clip;  // polygon clipper

int cellsTotal, cellsCalculated, cellsCalculatedLast;

PImage img, imgload, imgblur; 
PGraphics canvas;

Vec2D[] particles;
int[] particleRoute;

void LoadImageAndScale() {
  int tempx = 0;
  int tempy = 0;

  img = createImage(config.canvasWidth, config.canvasHeight, RGB);
  imgblur = createImage(config.canvasWidth, config.canvasHeight, RGB);

  img.loadPixels();

  if (config.invert) {
    for (int i = 0; i < img.pixels.length; i++) {
      img.pixels[i] = color(0);
    }
  } else {
    for (int i = 0; i < img.pixels.length; i++) {
      img.pixels[i] = color(255);
    }
  }

  img.updatePixels();

  if (config.inputImage != null) {
    imgload = loadImage(config.inputImage);
    fileLoaded = true;
  }

  if (config.display && config.selectInput && config.inputImage == null && !fileLoaded ) {
    noLoop();
    LOAD_FILE();
    return;
  }
  if ( fileLoaded == false) {
    // Load a demo image, at least until we have a "real" image to work with.
    imgload = loadImage("grace.jpg"); // Load demo image
  }

  imageRatio = (float) imgload.width / (float) imgload.height;
  mainRatio = (float) config.canvasWidth / (float) config.canvasHeight;
  windowRatio = (float) config.windowWidth / (float) config.windowHeight;

  println("Image: " + imgload.width + "x" + imgload.height);
  println("Ratio: " + imageRatio);
  println("Main : " + config.canvasWidth + "x" + config.canvasHeight);
  println("Ratio: " + mainRatio);

  //resize the image to fit within canvas size
  if ((imgload.width > config.canvasWidth) || (imgload.height > config.canvasHeight)) {
    if (imageRatio > mainRatio) { 
      imgload.resize(config.canvasWidth, 0);
    } else { 
      imgload.resize(0, config.canvasHeight);
    }
  } 

  if  (imgload.height < (config.canvasHeight - 2) ) { 
    tempy = (int) (( config.canvasHeight - imgload.height ) / 2) ;
  }
  if (imgload.width < (config.canvasWidth - 2)) {
    tempx = (int) (( config.canvasWidth - imgload.width ) / 2) ;
  }

  img.copy(imgload, 0, 0, imgload.width, imgload.height, tempx, tempy, imgload.width, imgload.height);

  //if (config.invert) {
  //  img.filter(INVERT);
  //} 

  if (config.gammaCorrection) {
    // Optional gamma correction for background image.  
    img.loadPixels();
   
    float tempFloat;  // Normally in the range 0.25 - 4.0
   
    for (int i = 0; i < img.pixels.length; i++) {
      tempFloat = brightness(img.pixels[i]) / 255;  
      img.pixels[i] = color(floor(255 * pow(tempFloat, config.gamma))); 
    } 
    
    img.updatePixels();
  }

  imgblur.copy(img, 0, 0, img.width, img.height, 0, 0, img.width, img.height);
  // This is a duplicate of the background image, that we will apply a blur to,
  // to reduce "high frequency" noise artifacts.

  imgblur.filter(BLUR, 1);  // Low-level blur filter to eliminate pixel-to-pixel noise artifacts.
  imgblur.loadPixels();
}

void MainArraysetup() { 
  // Main particle array initialization (to be called whenever necessary):
  LoadImageAndScale();
  // image(img, 0, 0); // SHOW BG IMG
  particles = new Vec2D[config.maxParticles];

  // Fill array by "rejection sampling"
  int  i = 0;
  while (i < config.maxParticles) {
    float fx = lowBorderX +  random(hiBorderX - lowBorderX);
    float fy = lowBorderY +  random(hiBorderY - lowBorderY);

    float p = brightness(imgblur.pixels[ floor(fy)*imgblur.width + floor(fx) ])/255; 
    // OK to use simple floor_ rounding here, because  this is a one-time operation,
    // creating the initial distribution that will be iterated.

    if (config.invert) {
      p =  1 - p;
    }

    if (random(1) >= p ) {  
      Vec2D p1 = new Vec2D(fx, fy);
      particles[i] = p1;  
      i++;
    }
  } 

  particleRouteLength = 0;
  Generation = 0; 
  millisLastFrame = millis();
  RouteStep = 0; 
  VoronoiCalculated = false;
  cellsCalculated = 0;
  vorPointsAdded = 0;
  voronoi = new Voronoi();  // Erase mesh
  TempShowCells = true;
  FileModeTSP = false;
} 

void settings () {
  config = new Config(sketchPath() + "/config.txt");
  if (config.display == true) {
    size(config.windowWidth, config.windowHeight, JAVA2D);
  }
}

void setup () {
  if (!config.display) {
    surface.setVisible(false);
  }
  canvas = createGraphics(config.canvasWidth, config.canvasHeight, JAVA2D);
  gfx = new ToxiclibsSupport(this, canvas);

  lowBorderX =  borderWidth; //config.canvasWidth*0.01; 
  hiBorderX = config.canvasWidth - borderWidth; //config.canvasWidth*0.98;
  lowBorderY = borderWidth; // config.canvasHeight*0.01;
  hiBorderY = config.canvasHeight - borderWidth;  //config.canvasHeight*0.98;

  int innerWidth = config.canvasWidth - 2  * borderWidth;
  int innerHeight = config.canvasHeight - 2  * borderWidth;

  clip = new SutherlandHodgemanClipper(new Rect(lowBorderX, lowBorderY, innerWidth, innerHeight));

  MainArraysetup();   // Main particle array setup

  config.maxDotSize = config.minDotSize * (1 + config.dotSizeFactor); //best way to do this?

  ReInitiallizeArray = false;
  showBG  = false;
  showPath = true;
  showCells = false;
  fileLoaded = false;
  SaveNow = 0;

  background(0); 
}

/***
 * Callback for selectInput() in LOAD_FILE.
 * Loads file if filetype is acceptable. 
 ***/
void fileSelected (File selection) {
  String[] acceptedExt = { "GIF", "JPG", "JPEG", "TGA", "PNG" };
  String[] parts;
  String loadPath;
  boolean fileOK = false;
  
  if (selection == null) {
    println("Window was closed or the user hit cancel.");
  } else {
    //println("User selected " + selection.getAbsolutePath());
    loadPath = selection.getAbsolutePath();

    // If a file was selected, print path to file 
    println("Loaded file: " + loadPath); 

    parts = splitTokens(loadPath, ".");

    for (int i = 0; i < acceptedExt.length; i++) {
      if ( parts[parts.length - 1].toUpperCase().equals(acceptedExt[i])) {
        fileOK = true;
        break;
      }
    }

    println("File OK: " + fileOK); 

    if (fileOK) {
      imgload = loadImage(loadPath); 
      fileLoaded = true;
      // MainArraysetup();
      ReInitiallizeArray = true;
    } else {
      // Can't load file
      ErrorDisplay = "ERROR: BAD FILE TYPE";
      ErrorTime = millis();
      ErrorDisp = true;
    }
  }
  LoadImageAndScale();
  loop();
}

void LOAD_FILE () {  
  println(":::LOAD JPG, GIF or PNG FILE:::");
  selectInput("Select a file to process:", "fileSelected");  // Opens file chooser
}

void SAVE_PATH() {  
  FileModeTSP = true;
  SAVE_SVG();
}

void SAVE_STIPPLES () {  
  FileModeTSP = false;
  SAVE_SVG();
}

void SaveFileSelected (File selection) {
  if (selection == null) {
    // If a file was not selected
    println("No output file was selected...");
    ErrorDisplay = "ERROR: NO FILE NAME CHOSEN.";
    ErrorTime = millis();
    ErrorDisp = true;
    exit();
  } else { 
    config.outputSVG = selection.getAbsolutePath();
    String[] p = splitTokens(config.outputSVG, ".");
    boolean fileOK = false;

    if ( p[p.length - 1].equals("SVG") ||  p[p.length - 1].equals("svg")) {
      fileOK = true;      
    }

    if (fileOK == false) {
      config.outputSVG = config.outputSVG + ".svg";
    }

    // If a file was selected, print path to folder 
    println("Save file: " + config.outputSVG);
    SaveNow = 1; 
    showPath  = true;

    ErrorDisplay = "SAVING FILE...";
    ErrorTime = millis();
    ErrorDisp = true;
  }
  loop();
}

void SAVE_SVG () {  
  noLoop();
  selectOutput("Output .svg file name:", "SaveFileSelected");
}

void QUIT(float theValue) { 
  exit();
}

void ORDER_ON_OFF(float theValue) {  
  if (showPath) {
    showPath  = false;
  } else {
    showPath  = true;
  }
} 

void CELLS_ON_OFF(float theValue) {  
  if (showCells) {
    showCells  = false;
  } else {
    showCells  = true;
  }
}  

void IMG_ON_OFF(float theValue) {  
  if (showBG) {
    showBG  = false;
  } else {
    showBG  = true;
  }
} 

void INVERT_IMG(float theValue) {  
  if (config.invert) {
    config.invert  = false;
  } else {
    config.invert  = true;
  }
  ReInitiallizeArray = true;
} 

void Stipples(int inValue) { 
  if (config.maxParticles != (int) inValue) {
    println("Update:  Stipple Count -> " + inValue); 
    ReInitiallizeArray = true;
  }
}

void Min_Dot_Size(float inValue) {
  if (config.minDotSize != inValue) {
    println("Update: Min_Dot_Size -> " + inValue);  
    config.minDotSize = inValue; 
    config.maxDotSize = config.minDotSize* (1 + config.dotSizeFactor);
  }
} 

void Dot_Size_Range(float inValue) {  
  if (config.dotSizeFactor != inValue) {
    println("Update: Dot Size Range -> " + inValue); 
    config.dotSizeFactor = inValue;
    config.maxDotSize = config.minDotSize* (1 + config.dotSizeFactor);
  }
} 

void White_Cutoff(float inValue) {
  if (config.cutoff != inValue) {
    println("Update: White_Cutoff -> "+inValue); 
    config.cutoff = inValue; 
    RouteStep = 0; // Reset TSP path
  }
} 

void  DoBackgrounds() {
  if (showBG) {
    canvas.image(img, 0, 0);    // Show original (cropped and scaled, but not blurred!) image in background
  } else { 
    if (config.invert) {
      canvas.background(0);
    } else {
      canvas.background(255);
    }
  }
}

void OptimizePlotPath () { 
  println("Optimizing plot path...");
  int temp;
  StatusDisplay = "Optimizing plotting path";
  Vec2D p1;

  if (RouteStep == 0) {
    float cutoffScaled = 1 - config.cutoff;
    // Begin process of optimizing plotting route, by flagging particles that will be shown.
    particleRouteLength = 0;

    boolean particleRouteTemp[] = new boolean[config.maxParticles]; 

    for (int i = 0; i < config.maxParticles; ++i) {
      particleRouteTemp[i] = false;

      int px = (int) particles[i].x;
      int py = (int) particles[i].y;

      if ((px >= imgblur.width) || (py >= imgblur.height) || (px < 0) || (py < 0)) {
        continue;
      }

      float v = (brightness(imgblur.pixels[ py*imgblur.width + px ]))/255; 

      if (config.invert) {
        v = 1 - v;
      }

      if (v < cutoffScaled) {
        particleRouteTemp[i] = true;   
        particleRouteLength++;
      }
    }

    particleRoute = new int[particleRouteLength]; 
    int tempCounter = 0;  
    for (int i = 0; i < config.maxParticles; ++i) { 
      if (particleRouteTemp[i]) {
        particleRoute[tempCounter] = i;
        tempCounter++;
      }
    }
    // These are the ONLY points to be drawn in the tour.
  }

  if (RouteStep < (particleRouteLength - 2)) { 

    // Nearest neighbor ("Simple, Greedy") algorithm path optimization:

    int StopPoint = RouteStep + 1000;      // 1000 steps per frame displayed; you can edit this number!

    if (StopPoint > (particleRouteLength - 1)) {
      StopPoint = particleRouteLength - 1;
    }

    for (int i = RouteStep; i < StopPoint; ++i) { 
      p1 = particles[particleRoute[RouteStep]];
      int ClosestParticle = 0; 
      float  distMin = Float.MAX_VALUE;

      for (int j = RouteStep + 1; j < (particleRouteLength - 1); ++j) { 
        Vec2D p2 = particles[particleRoute[j]];

        float  dx = p1.x - p2.x;
        float  dy = p1.y - p2.y;
        float  distance = (float) (dx*dx+dy*dy);  // Only looking for closest; do not need sqrt factor!

        if (distance < distMin) {
          ClosestParticle = j; 
          distMin = distance;
        }
      }  

      temp = particleRoute[RouteStep + 1];
      //        p1 = particles[particleRoute[RouteStep + 1]];
      particleRoute[RouteStep + 1] = particleRoute[ClosestParticle];
      particleRoute[ClosestParticle] = temp;

      if (RouteStep < (particleRouteLength - 1)) {
        RouteStep++;
      } else {
        println("Now optimizing plot path" );
      }
    }
  } else {     
    // Initial routing is complete
    // 2-opt heuristic optimization:
    // Identify a pair of edges that would become shorter by reversing part of the tour.

    for (int i = 0; i < config.testsPerFrame; i++) {   
      int indexA = floor(random(particleRouteLength - 1));
      int indexB = floor(random(particleRouteLength - 1));

      if (Math.abs(indexA  - indexB) < 2) {
        continue;
      }

      if (indexB < indexA) {  
        // swap A, B.
        temp = indexB;
        indexB = indexA;
        indexA = temp;
      }

      Vec2D a0 = particles[particleRoute[indexA]];
      Vec2D a1 = particles[particleRoute[indexA + 1]];
      Vec2D b0 = particles[particleRoute[indexB]];
      Vec2D b1 = particles[particleRoute[indexB + 1]];

      // Original distance:
      float  dx = a0.x - a1.x;
      float  dy = a0.y - a1.y;
      float  distance = (float) (dx*dx+dy*dy);  // Only a comparison; do not need sqrt factor! 
      dx = b0.x - b1.x;
      dy = b0.y - b1.y;
      distance += (float) (dx*dx+dy*dy);  //  Only a comparison; do not need sqrt factor! 

      // Possible shorter distance?
      dx = a0.x - b0.x;
      dy = a0.y - b0.y;
      float distance2 = (float) (dx*dx+dy*dy);  //  Only a comparison; do not need sqrt factor! 
      dx = a1.x - b1.x;
      dy = a1.y - b1.y;
      distance2 += (float) (dx*dx+dy*dy);  // Only a comparison; do not need sqrt factor! 

      if (distance2 < distance) {
        // Reverse tour between a1 and b0.   
        int indexhigh = indexB;
        int indexlow = indexA + 1;

        while (indexhigh > indexlow) {
          temp = particleRoute[indexlow];
          particleRoute[indexlow] = particleRoute[indexhigh];
          particleRoute[indexhigh] = temp;

          indexhigh--;
          indexlow++;
        }
      }
    }
  }

  frameTime = (millis() - millisLastFrame) / 1000;
  millisLastFrame = millis();
}

void doPhysics() {   
  // Iterative relaxation via weighted Lloyd's algorithm.
  int temp;
  int CountTemp;

  if (VoronoiCalculated == false){  
    // Part I: Calculate voronoi cell diagram of the points.

    StatusDisplay = "Calculating Voronoi diagram "; 

    //    float millisBaseline = millis();  // Baseline for timing studies
    //    println("Baseline.  Time = " + (millis() - millisBaseline) );

    if (vorPointsAdded == 0) {
      voronoi = new Voronoi();  // Erase mesh
    }

    temp = vorPointsAdded + 500;   // This line: VoronoiPointsPerPass  (Feel free to edit this number.)
    if (temp > config.maxParticles) {
      temp = config.maxParticles; 
    }

    for (int i = vorPointsAdded; i < temp; i++) {  
      // Optional, for diagnostics:::
      //  println("particles[i].x, particles[i].y " + particles[i].x + ", " + particles[i].y );

      voronoi.addPoint(new Vec2D(particles[i].x, particles[i].y ));
      vorPointsAdded++;
    }   

    if (vorPointsAdded >= config.maxParticles) {
      //    println("Points added.  Time = " + (millis() - millisBaseline) );
      cellsTotal =  (voronoi.getRegions().size());
      vorPointsAdded = 0;
      cellsCalculated = 0;
      cellsCalculatedLast = 0;

      RegionList = new Polygon2D[cellsTotal];

      int i = 0;
      for (Polygon2D poly : voronoi.getRegions()) {
        RegionList[i++] = poly;  // Build array of polygons
      }
      VoronoiCalculated = true;
    }
  } else{    
  // Part II: Calculate weighted centroids of cells.
    //  float millisBaseline = millis();
    //  println("fps = " + frameRate );

    StatusDisplay = "Calculating weighted centroids"; 

    // This line: CentroidsPerPass  (Feel free to edit this number.)
    // Higher values give slightly faster computation, but a less responsive GUI.
    // Default value: 500
    temp = cellsCalculated + config.centroidsPerPass;   

    if (temp > cellsTotal) {
      temp = cellsTotal;
    }

    for (int i=cellsCalculated; i< temp; i++) {  
      float xMax = 0;
      float xMin = config.canvasWidth;
      float yMax = 0;
      float yMin = config.canvasHeight;
      float xt, yt;

      Polygon2D region = clip.clipPolygon(RegionList[i]);

      for (Vec2D v : region.vertices) { 
        xt = v.x;
        yt = v.y;

        if (xt < xMin) {
          xMin = xt;
        }
        if (xt > xMax) {
          xMax = xt;
        }
        if (yt < yMin) {
          yMin = yt;
        }
        if (yt > yMax) {
          yMax = yt;
        }
      }
 
      float xDiff = xMax - xMin;
      float yDiff = yMax - yMin;
      float maxSize = max(xDiff, yDiff);
      float minSize = min(xDiff, yDiff);

      float scaleFactor = 1.0;

      // Maximum voronoi cell extent should be between
      // cellBuffer/2 and cellBuffer in size.

      while (maxSize > cellBuffer) {
        scaleFactor *= 0.5;
        maxSize *= 0.5;
      }

      while (maxSize < (cellBuffer/2)) {
        scaleFactor *= 2;
        maxSize *= 2;
      }  

      if ((minSize * scaleFactor) > (cellBuffer/2)) {
        // Special correction for objects of near-unity (square-like) aspect ratio, 
        // which have larger area *and* where it is less essential to find the exact centroid:
        scaleFactor *= 0.5;
      }

      float StepSize = (1/scaleFactor);

      float xSum = 0;
      float ySum = 0;
      float dSum = 0;       
      float PicDensity = 1.0; 

      if (config.invert) {
        for (float x=xMin; x<=xMax; x += StepSize) {
          for (float y=yMin; y<=yMax; y += StepSize) {

            Vec2D p0 = new Vec2D(x, y);
            if (region.containsPoint(p0)) { 

              // Thanks to polygon clipping, NO vertices will be beyond the sides of imgblur.  
              PicDensity = 0.001 + (brightness(imgblur.pixels[ round(y)*imgblur.width + round(x) ]));  

              xSum += PicDensity * x;
              ySum += PicDensity * y; 
              dSum += PicDensity;
            }
          }
        }  
      } else {
        for (float x=xMin; x<=xMax; x += StepSize) {
          for (float y=yMin; y<=yMax; y += StepSize) {
            Vec2D p0 = new Vec2D(x, y);
            if (region.containsPoint(p0)) {
              // Thanks to polygon clipping, NO vertices will be beyond the sides of imgblur. 
              PicDensity = 255.001 - (brightness(imgblur.pixels[ round(y)*imgblur.width + round(x) ]));  


              xSum += PicDensity * x;
              ySum += PicDensity * y; 
              dSum += PicDensity;
            }
          }
        }  
      }
      if (dSum > 0) {
        xSum /= dSum;
        ySum /= dSum;
      }

      Vec2D centr;

      float xTemp  = (xSum);
      float yTemp  = (ySum);

      if ((xTemp <= lowBorderX) || (xTemp >= hiBorderX) || (yTemp <= lowBorderY) || (yTemp >= hiBorderY)) {
        // If new centroid is computed to be outside the visible region, use the geometric centroid instead.
        // This will help to prevent runaway points due to numerical artifacts. 
        centr = region.getCentroid(); 
        xTemp = centr.x;
        yTemp = centr.y;

        // Enforce sides, if absolutely necessary:  (Failure to do so *will* cause a crash, eventually.)
        if (xTemp <= lowBorderX) {
          xTemp = lowBorderX + 1; 
        }
        if (xTemp >= hiBorderX) {
          xTemp = hiBorderX - 1; 
        }
        if (yTemp <= lowBorderY) {
          yTemp = lowBorderY + 1; 
        }
        if (yTemp >= hiBorderY) {
          yTemp = hiBorderY - 1;
        }
      }      

      particles[i].x = xTemp;
      particles[i].y = yTemp;

      cellsCalculated++;
    } 
    //  println("cellsCalculated = " + cellsCalculated );
    //  println("cellsTotal = " + cellsTotal );

    if (cellsCalculated >= cellsTotal) {
      VoronoiCalculated = false; 
      Generation++;
      frameTime = (millis() - millisLastFrame)/1000;
      millisLastFrame = millis();
    }
  }
}

/**
 * https://forum.processing.org/two/discussion/3506/point-on-an-outer-circle-intercepted-by-a-line-perpendicular-to-the-tangent-of-an-inner-circle
 * Calculate the points of intersection between a line and the
 * circumference of a circle.
 * [x0, y0] - [x1, y1] the line end coordinates 
 * [cx, cy] the centre of the circle
 * r the radius of the circle
 *
 * An array is returned that contains the intersection points in x, y order.
 * If the returned array is of length: 
 * 0 then there is no intersection 
 * 2 there is just one intersection (the line is a tangent to the circle) 
 * 4 there are two intersections 
 */
public float[] line_circle_p(float x0, float y0, float x1, float y1, float cx, float cy, float r) {
  float[] result = null;
  float f = (x1 - x0);
  float g = (y1 - y0);
  float fSQ = f*f;
  float gSQ = g*g;
  float fgSQ = fSQ + gSQ;
 
  float xc0 = cx - x0;
  float yc0 = cy - y0;
 
  float fygx = f*yc0 - g*xc0;
  float root = r*r*fgSQ - fygx*fygx;
  if (root > -ACCY) {
    float[] temp = null;
    int np = 0;
    float fxgy = f*xc0 + g*yc0;
    if (root < ACCY) {    // tangent so just one point
      float t = fxgy / fgSQ;
      temp = new float[] { 
        x0 + f*t, y0 + g*t
      };
      np = 2;
    }
    else {  // possibly two intersections
      temp = new float[4];
      root = sqrt(root);
      float t = (fxgy - root)/fgSQ;
      //     if (t >= 0 && t <= 1) {
      temp[np++] = x0 + f*t;
      temp[np++] = y0 + g*t;
      t = (fxgy + root)/fgSQ;
      temp[np++] = x0 + f*t;
      temp[np++] = y0 + g*t;
    }
    if (temp != null) {
      result = new float[np];
      System.arraycopy(temp, 0, result, 0, np);
    }
  }
  return (result == null) ? new float[0] : result;
}

/**
 * Create hatch lines within a circle determined by a line width
 *
 * x {float} center of circle on x axis
 * y {float} center of circle on y axis
 * d {float} diameter of circle
 * angle {float} angle of hatching, 0-360
 * line {float} width of line
 **/
ArrayList<float[]> fillCircle (float x, float y, float d, float angle, float line) {
  ArrayList<float[]> output = new ArrayList<float[]>();
  float r = (d / 2.0) - line;
  float perpAngle = (angle + 90.0) % 360.0;
  float perpRadian = radians(perpAngle);
  float radian = radians(angle);
  int lines = floor(d / line);
  float perpX = 0;
  float perpY = 0;
  float startX = 0;
  float startY = 0;
  float endX = 0;
  float endY = 0;
  float testX = 0;
  float testY = 0;
  float[] intersect;

  for (int i = -floor(lines / 2); i < floor(lines / 2); i++) {
    perpX = x + ((line * (i + 0.5)) * cos(perpRadian));
    perpY = y + ((line * (i + 0.5)) * sin(perpRadian));
    testX = perpX + (d * cos(radian));
    testY = perpY + (d * sin(radian));
    
    intersect = line_circle_p(perpX, perpY, testX, testY, x, y, r);

    if (intersect.length > 0) {
      startX = intersect[0];
      startY = intersect[1];
    } else {
      continue;
    }
    
    testX = startX - (d * cos(radian));
    testY = startY - (d * sin(radian));

    intersect = line_circle_p(perpX, perpY, testX, testY, x, y, r);

    if (intersect.length > 0) {
      endX = intersect[0];
      endY = intersect[1];
    } else {
      continue;
    }

    if (dist(startX, startY, endX, endY) > line) {
      float[] linePoints = {startX, startY, endX, endY};
      output.add(linePoints);
    }
  }
  return output;
}

void draw () {
  int i = 0;
  int temp;
  int scaledDimension;
  float dotScale = (config.maxDotSize - config.minDotSize);
  float cutoffScaled = 1 - config.cutoff;

  canvas.beginDraw();
  canvas.smooth();
  canvas.noStroke();


  if (ReInitiallizeArray) {
    MainArraysetup();
    ReInitiallizeArray = false;
  } 

  doPhysics();

  if ( showPath ) {
    canvas.stroke(128, 128, 255);   // Stroke color (blue)
    canvas.strokeWeight (1);

    for ( i = 0; i < (particleRouteLength - 1); ++i) {
      Vec2D p1 = particles[particleRoute[i]];
      Vec2D p2 = particles[particleRoute[i + 1]];

      canvas.line(p1.x, p1.y, p2.x, p2.y);
    }
  }

  if (config.invert) {
    canvas.stroke(255);
  } else {
    canvas.stroke(0);
  }

  // NOT in pause mode.  i.e., just displaying stipples.
  if (cellsCalculated == 0) {

    DoBackgrounds();

    if (Generation == 0) {
      TempShowCells = true;
    }

    if (showCells || TempShowCells) {  // Draw voronoi cells, over background.
      canvas.strokeWeight(1);
      canvas.noFill();

      if (config.invert && (showBG == false)) {  // TODO -- if config.invert AND NOT background
        canvas.stroke(100);
      } else {
        canvas.stroke(200);
      }
      //        stroke(200);

      i = 0;
      for (Polygon2D poly : voronoi.getRegions()) {
        //RegionList[i++] = poly; 
        gfx.polygon2D(clip.clipPolygon(poly));
      }
    }

    if (showCells) {
      // Show "before and after" centroids, when polygons are shown.
      // Normal w/ Min & Max dot size
      strokeWeight(config.minDotSize);  
      for ( i = 0; i < config.maxParticles; ++i) {

        int px = (int) particles[i].x;
        int py = (int) particles[i].y;

        if ((px >= imgblur.width) || (py >= imgblur.height) || (px < 0) || (py < 0)) {
          continue;
        }
        //Uncomment the following four lines, if you wish to display the "before" dots at weighted sizes.
        //float v = (brightness(imgblur.pixels[ py*imgblur.width + px ]))/255;  
        //if (config.invert)
        //v = 1 - v;
        //strokeWeight (config.maxDotSize - v * dotScale);  
        canvas.point(px, py);
      }
    }
  } else {
    // Stipple calculation is still underway
    if (TempShowCells) {
      DoBackgrounds(); 
      TempShowCells = false;
    }
    // stroke(0);   // Stroke color

    if (config.invert) {
      canvas.stroke(255);
    } else {
      canvas.stroke(0);
    }

    for ( i = cellsCalculatedLast; i < cellsCalculated; i++) {
      int px = (int) particles[i].x;
      int py = (int) particles[i].y;

      if ((px >= imgblur.width) || (py >= imgblur.height) || (px < 0) || (py < 0)) {
        continue;
      }
      
      float v = (brightness(imgblur.pixels[ py*imgblur.width + px ]))/255; 

      if (config.invert) {
        v = 1 - v;
      }

      if (v < cutoffScaled) { 
        canvas.strokeWeight(config.maxDotSize - v * dotScale);  
        canvas.point(px, py);
      }
    }

    cellsCalculatedLast = cellsCalculated;
  }

  canvas.endDraw();

  if (config.display) {
    if (mainRatio >= windowRatio) {
      scaledDimension = round((float) height * mainRatio);
      image(canvas, (width - scaledDimension) / 2, 0, scaledDimension, height);
    } else {
      scaledDimension = round((float) width / mainRatio);
      image(canvas, 0, (height - scaledDimension) / 2, width, scaledDimension);
    }
  } 

  if (Generation != lastGeneration) {
    if (!TempShowCells && config.outputImage != null) {
      canvas.save(config.outputImage);
    }
    println("Generation completed: " + Generation); 
    println("Generation time: " + frameTime + " s");
    lastGeneration = Generation;
  }

  if (ErrorDisp) {
    println(ErrorDisplay);
    if ((millis() - ErrorTime) > 8000) {
      ErrorDisp = false;
    }
  } else {
    if (!lastStatusDisplay.equals(StatusDisplay)) {
      println(StatusDisplay);
      lastStatusDisplay = StatusDisplay;
    }
  }

  if (Generation == config.maxGenerations) {
    SaveNow = 1;
  }

  if (SaveNow > 0 && config.display && config.outputSVG == null) {
    SAVE_SVG();
    return;
  }

  if (SaveNow > 0 && config.outputSVG != null) {
    OptimizePlotPath();
    StatusDisplay = "Saving SVG File";
    FileOutput = loadStrings("header.txt"); 
    String rowTemp;

    //Need to get some background on this.
    //what are these magic numbers?
    float SVGscale = (800.0 / (float) config.canvasHeight); 
    int xOffset = (int) (1536 - (SVGscale * config.canvasWidth / 2));
    int yOffset = (int) (1056  - (SVGscale * config.canvasHeight / 2));
    ArrayList<float[]> hatchLines;

    if (FileModeTSP) { 
      // Plot the PATH between the points only.
      println("Saving TSP File (SVG)");
      println(config.outputSVG);
      // Path header::
      rowTemp = "<path style=\"fill:none;stroke:black;stroke-width:2px;stroke-linejoin:round;stroke-linecap:round;\" d=\"M "; 
      FileOutput = append(FileOutput, rowTemp);

      for ( i = 0; i < particleRouteLength; ++i) {

        Vec2D p1 = particles[particleRoute[i]];  

        float xTemp = SVGscale*p1.x + xOffset;
        float yTemp = SVGscale*p1.y + yOffset;        

        rowTemp = xTemp + " " + yTemp + "\r";

        FileOutput = append(FileOutput, rowTemp);
      } 
      FileOutput = append(FileOutput, "\" />"); // End path description
    } else {
      println("Saving Stipple File (SVG)");
      println(config.outputSVG);
      for ( i = 0; i < particleRouteLength; ++i) {

        Vec2D p1 = particles[particleRoute[i]]; 

        int px = floor(p1.x);
        int py = floor(p1.y);

        float v = (brightness(imgblur.pixels[ py*imgblur.width + px ])) / 255;  

        if (config.invert) {
          v = 1 - v;
        }

        float dotrad = (config.maxDotSize - v * dotScale) / 2; 

        float xTemp = SVGscale * p1.x + xOffset;
        float yTemp = SVGscale * p1.y + yOffset; 

        rowTemp = "<circle cx=\"" + xTemp + "\" cy=\"" + yTemp + "\" r=\"" + dotrad +
          "\" style=\"fill:none;stroke:black;stroke-width:1;\"/>";
        // Typ:   <circle  cx="1600" cy="450" r="3" style="fill:none;stroke:black;stroke-width:2;"/>
        if (config.fill) {
          hatchLines = fillCircle(xTemp, yTemp, dotrad, 45.0, config.line);
          if (hatchLines.size() > 0) {
            for (float[] linePoints : hatchLines) {
              rowTemp += "<line x1=\"" + linePoints[0] + "\" y1=\"" + linePoints[1] + "\" x2=\"" + linePoints[2] + "\" y2=\"" + linePoints[3] + "\" style=\"fill:none;stroke:black;stroke-width:1;\"/>";
            }
          }
        }
        FileOutput = append(FileOutput, rowTemp);
      }
    }

    // SVG footer:
    FileOutput = append(FileOutput, "</g></g></svg>");
    saveStrings(config.outputSVG, FileOutput);
    FileModeTSP = false; // reset for next time

    if (FileModeTSP) {
      ErrorDisplay = "TSP Path .SVG file Saved";
    } else {
      ErrorDisplay = "Stipple .SVG file saved ";
    }

    ErrorTime = millis();
    ErrorDisp = true;
  } else if (SaveNow > 0 && config.outputSVG == null) {
    println("Exiting without exporting SVG");
  }

  if (SaveNow > 0) {
    exit();
  }
}